Left ventricular volume and ejection fraction assessment with transoesophageal echocardiography: 2D vs 3D imaging

Developments in transducer technology have enabled the use of three-dimensional transoesophageal echocardiography (3D TOE) in the operating theatre. Transthoracic echocardiography (TTE) 3D left ventricular (LV) volumes and ejection fraction (EF) agree better with magnetic resonance imaging (MRI) measurements, with less intra- and inter-observer variability compared with 2D. This has not been validated with 3D TOE. The aim of this study was to assess the bias, limits of agreement, and reproducibility of 3D TOE and 2D TOE LV volumes and EF in cardiac surgical patients.

Sixty-three patients having cardiac surgery with TOE were evaluated. LV volumes and EF were calculated using modified Simpson's method on 2D mid-oesophageal four- and two-chamber views, xPlane, and from a 3D full-volume data set. Intra- and inter-observer variability were assessed in a subset of 17 patients.

Real-time 3D TOE volume and EF assessment was possible in 59 of the 63 patients. Median end-diastolic volumes (EDVs) as measured by 2D, xPlane, and 3D techniques were 98.5, 94, and 97 ml. Median ESVs were 38.5, 40 and 35.6 ml. Median EFs were 58, 54 and 62.2%. There were no significant pairwise differences between these measurements. The limits of agreement for all comparisons were wide, and there were no statistically significant differences between the three methods in intra- or inter-observer variability.

The intraoperative use of 3D TOE to estimate LV volumes and EF has small bias compared with 2D assessments, wide limits of agreement, and no clear advantages compared with standard 2D TOE imaging in terms of LV volume and EF assessment.